United Nations peace envoy Lakhdar Brahimi hopes to persuade Syria’s President Bashar al-Assad to comply with a four-day truce during the Muslim holiday marking the Hajj, which begins Oct. 25, but many in the opposition remain skeptical about his plan.

Brahimi, who arrived in the capital Damascus on Friday afternoon, will meet Foreign Minister Walid al-Moualem on Saturday morning, said the U.N. spokesman in Damascus, Khaled al-Masri. He did not say whether the envoy would meet Assad.

"We will talk about the ceasefire and the Syrian issue in general. It is important to decrease the violence - we will talk with the government and political parties and civil society about the Syrian issue," Brahimi told reporters upon arrival.

The violence showed no sign of abating, with opposition activists reporting heavy street clashes in Aleppo, Syria's biggest city, and intensified army bombing of towns along the strategic north-south highway. U.N. Secretary-General Ban Ki-moon and Arab League chief Nabil Elaraby backed a ceasefire. "The longer the violence lasts, the more difficult it will be to find a political solution and rebuild Syria," they said in a joint statement.

Turkish Foreign Minister Ahmet Davutoglu called for all sides to observe the three- or four-day ceasefire.

"It is important that the Syrian regime, which bombards its own people with fighter planes and helicopters, halts these attacks immediately and unconditionally," Davutoglu said in Ankara.

Iran also backed the ceasefire call but added that the main problem in Syria was foreign interference - a reference to support for the rebels by Gulf Arab states, the United Sates and other Western powers, and Turkey.

"We consider the establishment of an immediate ceasefire an important step in helping the Syrian people," Iranian Deputy Foreign Minister Hossein Amir Abdullahian said, as quoted by Mehr news agency.

"Syria has taken important steps against terrorism and foreign interference and is pursuing political reforms and the security of the country."

Most opposition forces doubt Syria will comply with what they see as another toothless initiative. The largest opposition group, the Syrian National Council, has thrown its support behind the initiative but will hold the Syrian government responsible for any violation.

“The last time [a cease fire was agreed upon], the Syrians [who support Assad] violated it the first day. I hope this time they will respect it,” says Khaled Khoja, council representative and spokesman in Turkey. “I hope this time they will accept it, allow people to express their ideas peacefully, release prisoners and withdraw their forces from cities.”

Although Khoja says the Free Syrian Army, an umbrella organization for defected soldiers and armed opposition, has conditionally accepted the truce, its fighters will respond if attacked first by Syrian government forces. Khoja, like many in the opposition, worries that the initiative will fail because there is no penalty to compel the regime to observe the ceasefire.

“There must be a mechanism in order to make the Syrian regime comply. If there is no mechanism, the Syrian regime will continue to do the same.”

Rafif Jouejati, the Washington, D.C. based spokeswoman for the Local Coordination Committees, the largest activist network inside Syria, believes the truce is destined to fail.

“It is a feeble attempt by the international community that has no timeline, no consequences for failure to observe it, no consequences for continued bombardment. Since there are no consequences, any plan will fail and [Assad] will continue to kill civilians. It carries the same weight as a U.N. condemnation," she said.

U.N. Special Envoy Lakhdar Brahimi is calling for a four-day cease-fire in Syria next week to mark a Muslim holy day. NBC's Stephanie Gosk reports.

"Unless there are actual consequences, it is meaningless. I have relayed messages to Brahimi from the protesters: ‘Welcome to Syria on your mission impossible. Why didn’t you send Tom Cruise?’ It is an insult to the people who go out everyday and brave the bombing and bullets.”

Jouejati said this was the fourth attempt at brokering a ceasefire deal. “Assad has proven he is not going to look for political solutions. He has confirmed it through word and deed and will continue his security solution.”

A Britain-based monitoring group, the Syrian Observatory for Human Rights, doubts Brahimi’s ability to influence armed elements, whether they're on the opposition or government side. Brahimi cannot control Jebhat al Nusri, a jihadist militia, said director Rami Abdulrahman. "He cannot control what is happening on the ground," Abdulrahman said. "He doesn’t know how many Syrian troops are on the ground.”

More than 30,000 people have been killed over 19 months in the intensifying conflict.

There is little agreement among the many armed rebel militias who are temporarily unified by the desire to topple Assad. Although the Free Syrian Army reportedly supports the truce, a senior commander in Daraa, a Syrian city on the border with Jordan and the starting point of the revolution, told the British Guardian newspaper, “Brahimi’s proposal for a truce is stillborn.

“His project does not have any hope. Even if [exiled FSA leader] Riad al Assad accepts the truce, we will not. We will continue to fight," Staff Col. Ahmad Fahd al-Nimah, commander of the military council in Daraa, told the Guardian. "We represent those fighting on the ground in Syria. No one outside Syria can tell us what to do.”

An activist reached by phone in the same city told NBC News the people in the streets of Syria do not accept the ceasefire. Da’il, who gives only his first name for security purposes, believes the regime will use the ceasefire to fortify military positions.

“Before, when the Arab League and U.N. sent in peacekeeping observers, peaceful protesters were still being shot at. How can there be a ceasefire now, when there is nobody on the ground to observe it? No way will it work. Right now there is a roadblock with a sniper in front of me. If I walk out I will get shot. There is no way to stop the fighting. It is going on all the time,” he said.

Da’il went on to express the public’s cynicism toward the initiative: “There is a local saying here: If somebody tries something and fails, he is crazy if he tries the same thing again.”